Group 13 Electronic Configuration - NEET Notes, Formula & Common Mistakes
Group 13Electronic Configurationp-Block ElementsNEET ChemistryNEET 2025Boron familyValence electrons
Group 13 Electronic Configuration - NEET Notes, Formula & Common Mistakes
Some p-Block ElementsĀ·2 min readĀ·NEET 2026
What NEET Asks
Direct questions on valence shell electronic configurations of B, Al, Ga, In, Tl.
Understanding the role of d and f electrons in heavier elements.
Predicting group/period based on given configurations.
Key Points
Group 13 elements (Boron family) include Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), and Thallium (Tl).
Their general valence shell electronic configuration is nsĀ²npĀ¹.
Boron (Z=5): [He] 2sĀ²2pĀ¹
Aluminium (Z=13): [Ne] 3sĀ²3pĀ¹
Gallium (Z=31): [Ar] 3dĀ¹ā° 4sĀ²4pĀ¹ (Note the filled 3d orbitals, responsible for poor shielding)
Indium (Z=49): [Kr] 4dĀ¹ā° 5sĀ²5pĀ¹ (Note the filled 4d orbitals)
Thallium (Z=81): [Xe] 4fĀ¹ā“ 5dĀ¹ā° 6sĀ²6pĀ¹ (Note the filled 4f and 5d orbitals; crucial for understanding the inert pair effect)
Must-Know Formula / Reaction
General valence shell electronic configuration:nsĀ²npĀ¹
n: Principle quantum number of the outermost shell.
s: s-orbital, holding 2 electrons.
p: p-orbital, holding 1 electron.
Common Mistakes
Students often forget to include the filled d and f orbitals for heavier elements like Ga, In, and Tl, especially when writing full configurations.
Don't confuse the principal quantum number 'n' with the period number directly when d and f block elements are involved in the core.
Incorrectly identifying the correct noble gas core for elements, particularly for Thallium.
Rapid Revision
Group 13 elements uniformly have a valence configuration nsĀ²npĀ¹. Remember to account for the presence of filled 3dĀ¹ā° (Ga), 4dĀ¹ā° (In), and 4fĀ¹ā“ 5dĀ¹ā° (Tl) orbitals in their respective core configurations. These inner electrons are vital for explaining property trends.
Frequently Asked Questions
What is the general valence electronic configuration of Group 13 elements?ā¾
The general valence electronic configuration for all Group 13 elements is nsĀ²npĀ¹, where 'n' is the principal quantum number of the outermost shell. This configuration indicates that they all possess three valence electrons.
Why is the electronic configuration of Gallium different from Aluminium's core?ā¾
Gallium (Z=31) has a filled 3dĀ¹ā° subshell (e.g., [Ar] 3dĀ¹ā° 4sĀ²4pĀ¹) before its valence electrons, which is absent in Aluminium (Z=13) whose core is simply [Ne]. The presence of these 3d electrons, due to their poor shielding, significantly impacts properties like atomic radius and ionization enthalpy.
How does Thallium's electronic configuration reflect its position in the p-block?ā¾
Thallium (Z=81) has a complex electronic configuration of [Xe] 4fĀ¹ā“ 5dĀ¹ā° 6sĀ²6pĀ¹. The 4fĀ¹ā“ and 5dĀ¹ā° subshells are filled prior to its valence 6sĀ²6pĀ¹ electrons. This extensive core electron structure, particularly the f-orbitals, leads to very poor shielding effects, contributing to the 'inert pair effect' and unique properties of Thallium.
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